As a conventional sheet for attachment to the skin of the human body or others, a skin care sheet impregnated with a liquid such as a cosmetic preparation (a liquid-impregnated sheet for living-body application) is being used. The skin care sheet as typified by a facial mask (or a face mask or a facial mask sheet) simply allows the skin to be maintained in a highly wet (or moist) state, and a wide variety of commercial products is now being developed. Among them, the facial mask is formed from a sheet impregnated with a beauty essence and has a function of transferring the beauty essence to the skin. In order to transfer the beauty essence to the skin, the sheet itself requires closely adhering to the skin. Thus, for the purpose of successfully allowing the sheet of the facial mask to have contact with the skin, the sheet itself or the shape of the sheet has a variety of contrivances.
Japanese Patent Application Laid-Open Publication No. 2010-69287 (JP-2010-69287A, Patent Document 1) discloses a three-dimensional mask having a three-dimensional shape fitted to an irregular surface of a user's face; the mask comprises a left-side sheet and a right-side sheet which have mutually symmetrical shapes and each of which has a front edge portion, the front edge portions being opposed with respect to a median line of a user's face, wherein unattached portions of the left-side sheet and the right-side sheet are alienated from each other by bonding the front edge portions to each other with the surfaces of the front edge portions curved outward.
Unfortunately, the three-dimensional mask has an insufficient adhesion. In practical use, a user adjusts a portion that is out of close adhesion to the user's skin (a portion having a gap between the sheet and the user's skin) under pressure of the user's finger so as to allow the mask to closely adhere to the user's skin.
Meanwhile, as a material for a facial mask, a woven or nonwoven fabric made of fibers is commonly used. Patent Document 1 also discloses that the material for the three-dimensional mask includes a nonwoven fabric or a woven fabric, although Patent Document 1 is silent on the details of the nonwoven fabric or the woven fabric. Incidentally, a material to be commonly used for a facial mask includes a spunlace nonwoven fabric containing a cellulose-series fiber as a main component, as typified by a highly hydrophilic cotton.
International Publication WO2011/004834 (Patent Document 2) discloses a facial mask comprising a liquid-retaining layer and an adhesion layer; the liquid-retaining layer comprises a first nonwoven structural member comprising a first fiber and has an ability to absorb a liquid component, and the adhesion layer is contactable with a skin, is formed on at least one side of the liquid-retaining layer and is permeable to the liquid component, wherein the adhesion layer comprises a second nonwoven structural member comprising a second fiber, and the second fiber has a number-average fiber diameter of not more than 10 μm, and the thickness ratio of the adhesion layer relative to the liquid-retaining layer is 1/4 to 1/100 as a ratio of the adhesion layer/the liquid-retaining layer.
Unfortunately, this facial mask also has an insufficient adhesion to a skin. Meanwhile, a facial mask not only plays a role in skin care but also serves as a luxury (or discretionary) item for women. Thus the facial mask is required to have a high beauty effect and a high-grade feeling. In order to satisfy the beauty effect and the high-grade feeling, the quantity of an expensive beauty essence is increased. Thus, to retain the liquid (or the beauty essence), the facial mask is designed to have a high basis weight. Consequently, the facial mask is opaque, and it is difficult to visually confirm whether the facial mask is closely adhering to the skin during use.
Japanese Patent Application Laid-Open Publication No. 2001-170104 (JP-2001-170104A, Patent Document 3) discloses a cosmetic pack which comprises a nonwoven fabric composed of a carboxymethyl cellulose fiber and is allowed to swell in water or an aqueous solution at a time of use to cover a predetermined place of the skin.
Japanese Patent Application Laid-Open Publication No. 2011-127267 (JP-2011-127267A, Patent Document 4) discloses a porous cellulose gel that comprises a nonwoven fabric composed of a cellulose fiber having a carboxyl group chemically introduced thereinto by oxidizing only a primary hydroxyl group at the C-6 site in a glucose residue, and a liquid absorbed in the nonwoven fabric; the oxidized cellulose fiber has a substitution degree of 0.1 to 0.6. This document also discloses that the porous gel can be used for a cosmetic pack material.
Unfortunately, the nonwoven fabrics described in Patent Documents 3 and 4 have a low strength in a wet state, because the nonwoven fabrics, which are transparent, are obtained by gelating an extremely highly water-absorbing cellulose fiber having a carboxyl group. Thus each one of facial masks made of the nonwoven fabrics lacks a strength required to stretching of about 20 to 40% in a wet state and is hard to attach. It is difficult to allow the facial mask to fully adhere to (or fit with) the skin.